ARM: define two register utilities

Define arm_reg_current() ... returning handle to a given register,
and encapsulating the current mode's register shadowing.  It's got
one current use, for reporting the current register set to GDB.
This will let later patches clean up much ARMV4_5_CORE_REG_MODE()
nastiness, saving a bit of code.

Define and use arm_set_cpsr() ... initially it updates the cached
CPSR and sets up state used by arm_reg_current(), plus any SPSR
handle.   (Later: can also set up for T and J bits.)

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>

8 files changed, 122 insertions, 48 deletions

diff --git a/src/target/arm720t.c b/src/target/arm720t.c
index 4768f82d..ac7e4888 100644
--- a/src/target/arm720t.c
+++ b/src/target/arm720t.c
@@ -347,18 +347,20 @@ static int arm720t_soft_reset_halt(struct target *target)
 	target->state = TARGET_HALTED;
 
 	/* SVC, ARM state, IRQ and FIQ disabled */
-	buf_set_u32(armv4_5->cpsr->value, 0, 8, 0xd3);
+	uint32_t cpsr;
+
+	cpsr = buf_get_u32(armv4_5->cpsr->value, 0, 32);
+	cpsr &= ~0xff;
+	cpsr |= 0xd3;
+	arm_set_cpsr(armv4_5, cpsr);
 	armv4_5->cpsr->dirty = 1;
-	armv4_5->cpsr->valid = 1;
+	armv4_5->core_state = ARMV4_5_STATE_ARM;
 
 	/* start fetching from 0x0 */
 	buf_set_u32(armv4_5->core_cache->reg_list[15].value, 0, 32, 0x0);
 	armv4_5->core_cache->reg_list[15].dirty = 1;
 	armv4_5->core_cache->reg_list[15].valid = 1;
 
-	armv4_5->core_mode = ARMV4_5_MODE_SVC;
-	armv4_5->core_state = ARMV4_5_STATE_ARM;
-
 	arm720t_disable_mmu_caches(target, 1, 1, 1);
 	arm720t->armv4_5_mmu.mmu_enabled = 0;
 	arm720t->armv4_5_mmu.armv4_5_cache.d_u_cache_enabled = 0;
diff --git a/src/target/arm7_9_common.c b/src/target/arm7_9_common.c
index 7ca807a1..9580f62e 100644
--- a/src/target/arm7_9_common.c
+++ b/src/target/arm7_9_common.c
@@ -1227,18 +1227,20 @@ int arm7_9_soft_reset_halt(struct target *target)
 	register_cache_invalidate(armv4_5->core_cache);
 
 	/* SVC, ARM state, IRQ and FIQ disabled */
-	buf_set_u32(armv4_5->cpsr->value, 0, 8, 0xd3);
+	uint32_t cpsr;
+
+	cpsr = buf_get_u32(armv4_5->cpsr->value, 0, 32);
+	cpsr &= ~0xff;
+	cpsr |= 0xd3;
+	arm_set_cpsr(armv4_5, cpsr);
 	armv4_5->cpsr->dirty = 1;
-	armv4_5->cpsr->valid = 1;
+	armv4_5->core_state = ARMV4_5_STATE_ARM;
 
 	/* start fetching from 0x0 */
 	buf_set_u32(armv4_5->core_cache->reg_list[15].value, 0, 32, 0x0);
 	armv4_5->core_cache->reg_list[15].dirty = 1;
 	armv4_5->core_cache->reg_list[15].valid = 1;
 
-	armv4_5->core_mode = ARMV4_5_MODE_SVC;
-	armv4_5->core_state = ARMV4_5_STATE_ARM;
-
 	/* reset registers */
 	for (i = 0; i <= 14; i++)
 	{
@@ -1401,11 +1403,7 @@ static int arm7_9_debug_entry(struct target *target)
 	if (armv4_5->core_state == ARMV4_5_STATE_THUMB)
 		cpsr |= 0x20;
 
-	buf_set_u32(armv4_5->cpsr->value, 0, 32, cpsr);
-	armv4_5->cpsr->dirty = 0;
-	armv4_5->cpsr->valid = 1;
-
-	armv4_5->core_mode = cpsr & 0x1f;
+	arm_set_cpsr(armv4_5, cpsr);
 
 	if (!is_arm_mode(armv4_5->core_mode))
 	{
diff --git a/src/target/arm920t.c b/src/target/arm920t.c
index 9cd491f3..739df3ea 100644
--- a/src/target/arm920t.c
+++ b/src/target/arm920t.c
@@ -596,18 +596,20 @@ int arm920t_soft_reset_halt(struct target *target)
 	target->state = TARGET_HALTED;
 
 	/* SVC, ARM state, IRQ and FIQ disabled */
-	buf_set_u32(armv4_5->cpsr->value, 0, 8, 0xd3);
+	uint32_t cpsr;
+
+	cpsr = buf_get_u32(armv4_5->cpsr->value, 0, 32);
+	cpsr &= ~0xff;
+	cpsr |= 0xd3;
+	arm_set_cpsr(armv4_5, cpsr);
 	armv4_5->cpsr->dirty = 1;
-	armv4_5->cpsr->valid = 1;
+	armv4_5->core_state = ARMV4_5_STATE_ARM;
 
 	/* start fetching from 0x0 */
 	buf_set_u32(armv4_5->core_cache->reg_list[15].value, 0, 32, 0x0);
 	armv4_5->core_cache->reg_list[15].dirty = 1;
 	armv4_5->core_cache->reg_list[15].valid = 1;
 
-	armv4_5->core_mode = ARMV4_5_MODE_SVC;
-	armv4_5->core_state = ARMV4_5_STATE_ARM;
-
 	arm920t_disable_mmu_caches(target, 1, 1, 1);
 	arm920t->armv4_5_mmu.mmu_enabled = 0;
 	arm920t->armv4_5_mmu.armv4_5_cache.d_u_cache_enabled = 0;
diff --git a/src/target/arm926ejs.c b/src/target/arm926ejs.c
index 44afb2ce..7ecc7824 100644
--- a/src/target/arm926ejs.c
+++ b/src/target/arm926ejs.c
@@ -565,18 +565,20 @@ int arm926ejs_soft_reset_halt(struct target *target)
 	target->state = TARGET_HALTED;
 
 	/* SVC, ARM state, IRQ and FIQ disabled */
-	buf_set_u32(armv4_5->cpsr->value, 0, 8, 0xd3);
+	uint32_t cpsr;
+
+	cpsr = buf_get_u32(armv4_5->cpsr->value, 0, 32);
+	cpsr &= ~0xff;
+	cpsr |= 0xd3;
+	arm_set_cpsr(armv4_5, cpsr);
 	armv4_5->cpsr->dirty = 1;
-	armv4_5->cpsr->valid = 1;
+	armv4_5->core_state = ARMV4_5_STATE_ARM;
 
 	/* start fetching from 0x0 */
 	buf_set_u32(armv4_5->core_cache->reg_list[15].value, 0, 32, 0x0);
 	armv4_5->core_cache->reg_list[15].dirty = 1;
 	armv4_5->core_cache->reg_list[15].valid = 1;
 
-	armv4_5->core_mode = ARMV4_5_MODE_SVC;
-	armv4_5->core_state = ARMV4_5_STATE_ARM;
-
 	arm926ejs_disable_mmu_caches(target, 1, 1, 1);
 	arm926ejs->armv4_5_mmu.mmu_enabled = 0;
 	arm926ejs->armv4_5_mmu.armv4_5_cache.d_u_cache_enabled = 0;
diff --git a/src/target/armv4_5.c b/src/target/armv4_5.c
index 01d3bc30..3156c666 100644
--- a/src/target/armv4_5.c
+++ b/src/target/armv4_5.c
@@ -245,6 +245,10 @@ static const struct {
 	unsigned cookie;
 	enum armv4_5_mode mode;
 } arm_core_regs[] = {
+	/* IMPORTANT:  we guarantee that the first eight cached registers
+	 * correspond to r0..r7, and the fifteenth to PC, so that callers
+	 * don't need to map them.
+	 */
 	{ .name = "r0", .cookie = 0, .mode = ARMV4_5_MODE_ANY, },
 	{ .name = "r1", .cookie = 1, .mode = ARMV4_5_MODE_ANY, },
 	{ .name = "r2", .cookie = 2, .mode = ARMV4_5_MODE_ANY, },
@@ -255,7 +259,8 @@ static const struct {
 	{ .name = "r7", .cookie = 7, .mode = ARMV4_5_MODE_ANY, },
 
 	/* NOTE: regs 8..12 might be shadowed by FIQ ... flagging
-	 * them as MODE_ANY creates special cases.
+	 * them as MODE_ANY creates special cases.  (ANY means
+	 * "not mapped" elsewhere; here it's "everything but FIQ".)
 	 */
 	{ .name = "r8", .cookie = 8, .mode = ARMV4_5_MODE_ANY, },
 	{ .name = "r9", .cookie = 9, .mode = ARMV4_5_MODE_ANY, },
@@ -267,6 +272,7 @@ static const struct {
 	{ .name = "sp_usr", .cookie = 13, .mode = ARMV4_5_MODE_USR, },
 	{ .name = "lr_usr", .cookie = 14, .mode = ARMV4_5_MODE_USR, },
 
+	/* guaranteed to be at index 15 */
 	{ .name = "pc", .cookie = 15, .mode = ARMV4_5_MODE_ANY, },
 
 	{ .name = "r8_fiq", .cookie = 8, .mode = ARMV4_5_MODE_FIQ, },
@@ -333,6 +339,73 @@ const int armv4_5_core_reg_map[8][17] =
 	}
 };
 
+/**
+ * Configures host-side ARM records to reflect the specified CPSR.
+ * Later, code can use arm_reg_current() to map register numbers
+ * according to how they are exposed by this mode.
+ */
+void arm_set_cpsr(struct arm *arm, uint32_t cpsr)
+{
+	enum armv4_5_mode mode = cpsr & 0x1f;
+	int num;
+
+	/* NOTE:  this may be called very early, before the register
+	 * cache is set up.  We can't defend against many errors, in
+	 * particular against CPSRs that aren't valid *here* ...
+	 */
+	if (arm->cpsr) {
+		buf_set_u32(arm->cpsr->value, 0, 32, cpsr);
+		arm->cpsr->valid = 1;
+		arm->cpsr->dirty = 0;
+	}
+
+	arm->core_mode = mode;
+
+	/* mode_to_number() warned; set up a somewhat-sane mapping */
+	num = armv4_5_mode_to_number(mode);
+	if (num < 0) {
+		mode = ARMV4_5_MODE_USR;
+		num = 0;
+	}
+
+	arm->map = &armv4_5_core_reg_map[num][0];
+	arm->spsr = (mode == ARMV4_5_MODE_USR || mode == ARMV4_5_MODE_SYS)
+			? NULL
+			: arm->core_cache->reg_list + arm->map[16];
+}
+
+/**
+ * Returns handle to the register currently mapped to a given number.
+ * Someone must have called arm_set_cpsr() before.
+ *
+ * \param arm This core's state and registers are used.
+ * \param regnum From 0..15 corresponding to R0..R14 and PC.
+ *	Note that R0..R7 don't require mapping; you may access those
+ *	as the first eight entries in the register cache.  Likewise
+ *	R15 (PC) doesn't need mapping; you may also access it directly.
+ *	However, R8..R14, and SPSR (arm->spsr) *must* be mapped.
+ *	CPSR (arm->cpsr) is also not mapped.
+ */
+struct reg *arm_reg_current(struct arm *arm, unsigned regnum)
+{
+	struct reg *r;
+
+	if (regnum > 16)
+		return NULL;
+
+	r = arm->core_cache->reg_list + arm->map[regnum];
+
+	/* e.g. invalid CPSR said "secure monitor" mode on a core
+	 * that doesn't support it...
+	 */
+	if (!r) {
+		LOG_ERROR("Invalid CPSR mode");
+		r = arm->core_cache->reg_list + regnum;
+	}
+
+	return r;
+}
+
 static const uint8_t arm_gdb_dummy_fp_value[12];
 
 /**
@@ -446,10 +519,9 @@ static int armv4_5_set_core_reg(struct reg *reg, uint8_t *buf)
 		{
 			LOG_DEBUG("changing ARM core mode to '%s'",
 					arm_mode_name(value & 0x1f));
-			armv4_5_target->core_mode = value & 0x1f;
 			armv4_5_target->write_core_reg(target, reg,
 					16, ARMV4_5_MODE_ANY, value);
-			reg->dirty = 0;
+			arm_set_cpsr(armv4_5_target, value);
 		}
 	}
 
@@ -752,14 +824,10 @@ int armv4_5_get_gdb_reg_list(struct target *target, struct reg **reg_list[], int
 	*reg_list = malloc(sizeof(struct reg*) * (*reg_list_size));
 
 	for (i = 0; i < 16; i++)
-	{
-		(*reg_list)[i] = &ARMV4_5_CORE_REG_MODE(armv4_5->core_cache, armv4_5->core_mode, i);
-	}
+		(*reg_list)[i] = arm_reg_current(armv4_5, i);
 
 	for (i = 16; i < 24; i++)
-	{
 		(*reg_list)[i] = &arm_gdb_dummy_fp_reg;
-	}
 
 	(*reg_list)[24] = &arm_gdb_dummy_fps_reg;
 	(*reg_list)[25] = armv4_5->cpsr;
@@ -805,7 +873,6 @@ int armv4_5_run_algorithm_inner(struct target *target, int num_mem_params, struc
 	struct armv4_5_common_s *armv4_5 = target_to_armv4_5(target);
 	struct armv4_5_algorithm *armv4_5_algorithm_info = arch_info;
 	enum armv4_5_state core_state = armv4_5->core_state;
-	enum armv4_5_mode core_mode = armv4_5->core_mode;
 	uint32_t context[17];
 	uint32_t cpsr;
 	int exit_breakpoint_size = 0;
@@ -835,6 +902,9 @@ int armv4_5_run_algorithm_inner(struct target *target, int num_mem_params, struc
 		return ERROR_FAIL;
 	}
 
+	/* save r0..pc, cpsr-or-spsr, and then cpsr-for-sure;
+	 * they'll be restored later.
+	 */
 	for (i = 0; i <= 16; i++)
 	{
 		struct reg *r;
@@ -952,6 +1022,7 @@ int armv4_5_run_algorithm_inner(struct target *target, int num_mem_params, struc
 		}
 	}
 
+	/* restore everything we saved before (17 or 18 registers) */
 	for (i = 0; i <= 16; i++)
 	{
 		uint32_t regvalue;
@@ -964,12 +1035,11 @@ int armv4_5_run_algorithm_inner(struct target *target, int num_mem_params, struc
 			ARMV4_5_CORE_REG_MODE(armv4_5->core_cache, armv4_5_algorithm_info->core_mode, i).dirty = 1;
 		}
 	}
-	buf_set_u32(armv4_5->cpsr->value, 0, 32, cpsr);
-	armv4_5->cpsr->valid = 1;
+
+	arm_set_cpsr(armv4_5, cpsr);
 	armv4_5->cpsr->dirty = 1;
 
 	armv4_5->core_state = core_state;
-	armv4_5->core_mode = core_mode;
 
 	return retval;
 }
@@ -1169,8 +1239,8 @@ int armv4_5_init_arch_info(struct target *target, struct arm *armv4_5)
 	target->arch_info = armv4_5;
 
 	armv4_5->common_magic = ARMV4_5_COMMON_MAGIC;
+	arm_set_cpsr(armv4_5, ARMV4_5_MODE_USR);
 	armv4_5->core_state = ARMV4_5_STATE_ARM;
-	armv4_5->core_mode = ARMV4_5_MODE_USR;
 
 	/* core_type may be overridden by subtype logic */
 	armv4_5->core_type = ARMV4_5_MODE_ANY;
diff --git a/src/target/armv4_5.h b/src/target/armv4_5.h
index 5bce30b3..a9599c82 100644
--- a/src/target/armv4_5.h
+++ b/src/target/armv4_5.h
@@ -85,6 +85,11 @@ struct arm
 	/** Handle to the CPSR; valid in all core modes. */
 	struct reg *cpsr;
 
+	/** Handle to the SPSR; valid only in core modes with an SPSR. */
+	struct reg *spsr;
+
+	const int *map;
+
 	/**
 	 * Indicates what registers are in the ARM state core register set.
 	 * ARMV4_5_MODE_ANY indicates the standard set of 37 registers,
@@ -161,6 +166,9 @@ int arm_checksum_memory(struct target *target,
 int arm_blank_check_memory(struct target *target,
 		uint32_t address, uint32_t count, uint32_t *blank);
 
+void arm_set_cpsr(struct arm *arm, uint32_t cpsr);
+struct reg *arm_reg_current(struct arm *arm, unsigned regnum);
+
 extern struct reg arm_gdb_dummy_fp_reg;
 extern struct reg arm_gdb_dummy_fps_reg;
 
diff --git a/src/target/cortex_a8.c b/src/target/cortex_a8.c
index 24632099..71de3b79 100644
--- a/src/target/cortex_a8.c
+++ b/src/target/cortex_a8.c
@@ -648,7 +648,7 @@ static int cortex_a8_debug_entry(struct target *target)
 	dap_ap_select(swjdp, swjdp_debugap);
 	LOG_DEBUG("cpsr: %8.8" PRIx32, cpsr);
 
-	armv4_5->core_mode = cpsr & 0x1F;
+	arm_set_cpsr(armv4_5, cpsr);
 
 	i = (cpsr >> 5) & 1;	/* T */
 	i |= (cpsr >> 23) & 1;	/* J << 1 */
@@ -674,11 +674,6 @@ static int cortex_a8_debug_entry(struct target *target)
 	}
 
 	/* update cache */
-	reg = armv4_5->cpsr;
-	buf_set_u32(reg->value, 0, 32, cpsr);
-	reg->valid = 1;
-	reg->dirty = 0;
-
 	for (i = 0; i <= ARM_PC; i++)
 	{
 		reg = &ARMV4_5_CORE_REG_MODE(armv4_5->core_cache,
diff --git a/src/target/xscale.c b/src/target/xscale.c
index 3ed7bf0b..659caec1 100644
--- a/src/target/xscale.c
+++ b/src/target/xscale.c
@@ -948,12 +948,9 @@ static int xscale_debug_entry(struct target *target)
 		LOG_DEBUG("r%i: 0x%8.8" PRIx32 "", i, buffer[i + 1]);
 	}
 
-	buf_set_u32(armv4_5->cpsr->value, 0, 32, buffer[9]);
-	armv4_5->cpsr->dirty = 1;
-	armv4_5->cpsr->valid = 1;
+	arm_set_cpsr(armv4_5, buffer[9]);
 	LOG_DEBUG("cpsr: 0x%8.8" PRIx32 "", buffer[9]);
 
-	armv4_5->core_mode = buffer[9] & 0x1f;
 	if (!is_arm_mode(armv4_5->core_mode))
 	{
 		target->state = TARGET_UNKNOWN;